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19-2716; Rev 0a; 1/03
MAX5052A Evaluation Kit
General Description
The MAX5052A evaluation kit (EV kit) is a fully assembled and tested circuit board that contains a 9W flyback DC-to-DC converter. The circuit is configured for output voltages of +5V and +15V and provides up to 1.5A and 100mA of current at each respective output. Power for the circuit can be provided from either a +36VDC to +72VDC or -36VDC to -72VDC source. High efficiency up to 83% is achieved using a singletransistor, flyback DC-to-DC converter topology. The surface-mount transformer provides up to 1500V galvanic isolation of both outputs. Low cost is achieved through the use of primary-side regulation while undervoltage lockout (UVLO), digital soft-start, and thermal shutdown provide for a robust 9W isolated power supply. Operation at 262kHz allows the use of small magnetics and output capacitors. Warning: The MAX5052A EV kit is designed to operate with high voltages. Dangerous voltages are present on the MAX5052A EV kit and on equipment connected to it. Users who power up the MAX5052A EV kit or power the sources connected to it must be careful to follow safety procedures appropriate to working with highvoltage electrical equipment. Under severe fault or failure conditions, the MAX5052A EV kit may dissipate large amounts of power, which could result in the mechanical ejection of a component or of component debris at high velocity. Operate MAX5052A EV kit with care to avoid possible personal injury.
Features
o +36VDC to +72VDC or -36VDC to -72VDC Input Voltage Range o Isolated Outputs VOUT1: +5V Provides Up to 1.5A VOUT2: +15V Provides Up to 100mA o 5% (typ) Load Regulation for the +5V Output (150mA to 1.5A) o 83% Efficiency at 48V Input and Full Load o Cycle-by-Cycle Current Limit o 262kHz Switching Frequency o Digital Soft-Start o Undervoltage Lockout (UVLO) o Designed for 1500V Isolation with Primary-Side Regulation o Low-Cost Flyback Design o Fully Assembled and Tested
Evaluates: MAX5052A
Ordering Information
PART MAX5052AEVKIT TEMP RANGE 0C to +70C IC PACKAGE 8 MAX
Component Suppliers
SUPPLIER Central Semiconductor Cooper-Coiltronics Dale-Vishay Diodes Inc. Fair-Rite Products International Rectifier Kemet Murata Panasonic TDK Telefunken-Vishay Zetex USA PHONE 631-435-1110 561-752-5000 402-564-3131 805-446-4800 845-895-2055 310-322-3331 864-963-6300 770-436-1300 714-373-7366 847-803-6100 402-563-6325 631-543-7100 FAX 631-435-1824 561-742-1178 402-563-6296 805-446-4850 845-895-2629 310-726-8721 864-963-6322 770-436-3030 714-737-7323 847-390-4405 N/A 631-864-7630 WEBSITE www.centralsemi.com www.cooperet.com www.vishay.com www.diodes.com www.fair-rite.com www.irf.com www.kemet.com www.murata.com www.panasonic.com www.component.tdk.com www.vishay.com www.zetex.com
Note: Please indicate that you are using the MAX5052A when contacting these component suppliers. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX5052A Evaluation Kit Evaluates: MAX5052A
Component List
DESIGNATION C1, C2 QTY 2 DESCRIPTION 1F 10%, 100V X7R ceramic capacitors (1812) TDK C4532X7R2A105K 68F, 6.3V electrolytic capacitor (V case) Kemet A700V686M006AT 22F 20%, 6.3V X5R ceramic capacitor (1206) TDK C3216X5R0J226M 47F, 25V electrolytic capacitor (6.3 x 5.8) Panasonic EEVFK1E470P 0.0047F 10%, 250VAC X7R ceramic capacitor (2220) Murata GA355DR7GC472KY02L 0.22F 10%, 50V X7R ceramic capacitors (0805) Murata GRM21BR71H224KA01B Not installed, ceramic capacitors (0603) 2200pF 10%, 50V X7R ceramic capacitor (0603) TDK C1608X7R1H222K 1F 10%, 16V X7R ceramic capacitor (0805) TDK C2012X7R1C105KT 0.022F 10%, 50V X7R ceramic capacitor (0603) TDK C1608X7R1H223KT 1F 10%, 25V X7R ceramic capacitor (0805) TDK C2012X7R1E105KT 15F 10%, 35V tantalum capacitor (D case) Kemet T491D156K035AS Not installed, ceramic capacitor (0805) 40V, 10A Schottky diode (POWERMITE 3) Diodes Inc. SBM1040 DESIGNATION D2 QTY 1 DESCRIPTION 200V, 1.5A super-fast diode (SMD) Vishay/Telefunken BYG20D Not installed; 250V, 250mA highvoltage switching diode (SOD-123) Central Semiconductor CMHD2003 (when used) 5.6V, 0.5W zener diode (SOD-123) Diodes Inc. BZT52C5V6 18V, 0.5W zener diode (SOD-123) Diodes Inc. BZT52C18 75V, 250mA high-speed diode (SOT23) Central Semiconductor CMPD914 Not installed; 14V, 250mW zener diode (SOD-323) Central Semiconductor CMDZ5244B (when used) 40V 0.5A Schottky diode (SOT23) Zetex ZHCS500 2-pin header 3A ferrite bead inductor (1806) Fair-Rite 2518066007Y3 100mA ferrite bead inductor (0805) Fair-Rite 2508051027Y0 200V, 1.2A N-channel MOSFET (8-pin SO) International Rectifier IRF7464 22.6k 1% resistor (0603) 2.49k 1% resistor (0603) 1M 1% resistor (0805) 42.2k 1% resistor (0805) 0.170 1% power resistor (1206) Dale-Vishay WSL-12060.170 1% 33k 5% resistor (1206) 1.2k 5% resistors (1206) Not installed 14.3k 1% resistor (0603) 0 5% resistor (0805) 100 5% resistor (0603)
C3
1
D3
0
D4 D5
1 1
C4
1
C5
1
D6
1
C6
1
D7
0
C7, C11, C12
3
D8 JU1 L1 L2
1 1 1 1
C8, C10
0
C9
1
C13
1
N1 R1 R2 R3 R4 R5 R6 R7, R12 R8 R9 R10 R11
1 1 1 1 1 1 1 2 0 1 1 1
C14
1
C15
1
C16
1
C17
0
D1
1
2
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MAX5052A Evaluation Kit
Component List (continued)
DESIGNATION T1 U1 None None QTY 1 1 1 1 DESCRIPTION 35H, 10W transformer (10-pin Gull Wing) Cooper-Coiltronics CTX03-16034 MAX5052AEUA (8-pin MAX) Shunt (JU1) MAX5052A PC board
Detailed Description
The MAX5052A EV kit is a 9W, isolated flyback DC-to-DC converter that provides +5V and +15V outputs. The +5V output, VOUT1, can provide up to 1.5A and the +15V output, VOUT2, can provide up to 100mA. The circuit can be powered from a +36VDC to +72VDC or a -36VDC to -72VDC source. The user must supply at least 22F of bulk-storage capacitance at the input terminals (+VIN, -VIN). The capacitor should be rated for 100V and be able to carry approximately 200mA of ripple current. The flyback DC-to-DC converter achieves up to 83% efficiency. The single-transistor topology and primaryside regulation provide for a low-cost design by eliminating the need for an optocoupler and shunt reference on the secondary side. The MAX5052 EV kit provides cycle-by-cycle, primary-side current-limit protection. The current-sense resistor, R5, senses the current through the transformer's (T1) primary winding. Switching transistor (N1) turns off when the trip level of 291mV is reached. The surface-mount transformer provides galvanic isolation up to 1500V for both outputs. The MAX5052A EV kit features PC board pads for an RCD snubber network (R8, C10, D3) to minimize leakage-energy ringing and to clamp the voltage at the drain of MOSFET (N1) during switching (with most MOSFETs, this snubber circuit can be eliminated). Primary-side regulation through feedback resistors R1, R2, rectifier D6, and the T1 tertiary winding provides 5% regulation for the outputs. R7 and R12 are adjusted to preload the tertiary winding for the +5V 5% output regulation. UVLO provides controlled turn-on and shutdown during brownouts when powering up or powering down. The UVLO settings can be changed by replacing R4. Startup resistor R6 and reservoir capacitor C16 enable the MAX5052A to start up within approximately 500ms. The digital soft-start allows the output voltage to slowly ramp up in a controlled manner within 60ms. The MAX5052A controller switches at a fixed 262kHz frequency and the duty cycle is varied to control energy transfer to the isolated outputs. The maximum duty cycle is 50% for the MAX5052A EV kit's discontinuous currentmode flyback design.
Evaluates: MAX5052A
Quick Start
The MAX5052A EV kit is fully assembled and tested. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed.
Outputs
1) Connect a voltmeter to the VOUT1 pad and SGND. 2) Connect a second voltmeter to the VOUT2 pad and SGND. 3) Connect a 750mA load to VOUT1 and a 50mA load to VOUT2. 4) Verify that a shunt is not installed across the pins of jumper JU1 (SHDN). 5) Connect a +36V to +72V power supply to the +VIN pad. Do not exceed 100V input voltage. Connect the power supply's ground to the -VIN pad. 6) Turn on the power supply above +36V and verify that the voltmeter at VOUT1 reads approximately +5V. 7) Verify that the voltmeter at VOUT2 reads approximately +15V. The maximum current for each output should be limited to less than 1.5A for VOUT1 and 100mA for VOUT2. For instructions on selecting the feedback resistors for other output voltages, see the Evaluating Other Output Voltages, Current Limits, and UVLO section.
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MAX5052A Evaluation Kit Evaluates: MAX5052A
Table 1. Jumper JU1 Shutdown Mode
SHUNT LOCATION None Installed MAX5052A UVLO/EN Pin UVLO resistors R3 and R4 determine startup voltage Pulled low to -VIN MAX5052A OUTPUT MAX5052A enabled: VOUT1 = +5V VOUT2 = +15V Shutdown mode
VOUT1 number of turns = 6, VFB is the MAX5052A reference voltage = 1.23V, VVD6 is the circuit's tertiary-winding high-speed diode (D6) forward-voltage drop = 1.0V, VVD1 is the circuit's secondary-side Schottky diode (D1) forward-voltage drop of 0.45V (typ). Both output voltages are scaled up or down since the respective transformer's secondary-output turns set the actual voltage. Additionally, the maximum current for each output should be limited to less than 1.5A for VOUT1 and 100mA for VOUT2. Current Limiting The MAX5052A EV kit features current limiting for the transformer's primary current. The MAX5052A IC turns off switching MOSFET N1 when the voltage at the MAX5052A CS pin reaches 291mV. Current-sense resistor R5 (0.170) limits the transformer peak-primary current to 1.71A (291mV/0.170 = 1.71A). This limits the average short-circuit current on the secondary outputs typically to 1.2A (average) and 200mA (average) for VOUT1 and VOUT2, respectively. To evaluate a lower current limit, R5 must be replaced with a different surface-mount resistor (1206 size) as determined by the following equation: R5 = VSENSE IPRIMARY
Shutdown Mode and Remote-Control Method
The MAX5052A EV kit features two methods to shut down the flyback DC-to-DC converter. Jumper JU1 can be used to shut down the flyback DC-to-DC converter. An alternate method, remote control shutdown, can be achieved with a user-supplied open collector/drain transistor or relay contact connected to the SHDN and -VIN pads of the MAX5052A EV kit. Table 1 lists the shutdown mode.
Evaluating Other Output Voltages, Current Limits, and UVLO
VOUT1 and VOUT2 Output Voltages The MAX5052A EV kit's outputs, VOUT1 and VOUT2, are set to +5V and +15V, respectively, by transformer T1's tertiary turns. The transformer's respective secondary-output turns, and the resistor-dividers R1 and R2 set the output voltages. To generate scaled-output voltages other than +5V (+4.2V to +6.8V) and +15V (+12.3V to +20.2V), select different voltage-divider resistors (R1, R2). R2 is typically chosen to be less than 5k. When evaluating other output voltages, verify that the secondary outputs' components affected by increased voltage are rated appropriately. Components D1, C3, C4, C13, and D4 of VOUT1 and components D2, C5, C15, and D5 should have their respective voltage rating evaluated. Using the desired scaled-output voltages, calculate R1 using the following equation: NT ( VOUT1 - VVD1 ) x N1 - VVD6 - 1 x R2 R1 = VFB where VOUT1 is the +5V output, NT is the transformer's tertiary turns = 15, N1 is the transformer's secondary
where V SENSE = 291mV and I PRIMARY is the transformer's maximum primary current. Undervoltage Lockout (UVLO) The MAX5052A EV kit features a UVLO circuit that prevents operation below the programmed input-supply start voltage. R3 and R4 set the voltage at the MAX5052A's UVLO/EN pin that determines the UVLO wakeup and shutdown levels, 1.28V (typ) and 1.23V (typ), respectively. To evaluate other wakeup and shutdown levels, replace R4 with another surface-mount resistor (0805 size). Refer to the MAX5052/MAX5053 Undervoltage Lockout section in the MAX5052/ MAX5053 data sheet for instructions on selecting R4 as determined by the following equation: R3 = ((VIN - VUVLO) / VUVLO) x R4 where VIN is the 36V to 72V supply voltage applied between the +VIN and -VIN pads of the MAX5052A EV kit and VUVLO = 1.28V (typ).
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MAX5052A Evaluation Kit
Flyback Converter Waveforms
Evaluates: MAX5052A
EFFICIENCY vs. OUTPUT CURRENT
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 0.15 0.30 0.45 0.60 0.75 0.90 1.05 1.20 1.35 1.50 IOUT1 (A) 10ms/div 0V 5V/div VOUT2 = +15V, 25mA 0V 2V/div VOUT2 VOUT2 = +15V, 100mA VOUT1
Figure 1. Efficiency vs. Output Current IOUT1, +VIN = 48V
Figure 2. Output Voltage Transient at Power-Up, +VIN = 48V, Channel 1 = VOUT1 (IOUT1 = 150mA), Channel 2 = VOUT2 (IOUT2 = 25mA)
VOUT1 REGULATION vs. IOUT1
6.0 5.8 5.6 5.4 VOUT1 (V) VOUT2 (V) 5.2 5.0 4.8 4.6 4.4 4.2 4.0 0 0.30 0.60 0.90 1.20 1.50 IOUT1 (A) VOUT2 = +15V, 100mA VOUT2 = +15V, 25mA 18.0 17.6 17.2 16.8 16.4 16.0 15.6 15.2 14.8 14.4 14.0 0
VOUT2 REGULATION vs. IOUT2
VOUT1 = +5V, 150mA
VOUT1 = +5V, 1.5A
0.02
0.04
0.06
0.08
0.10
IOUT2 (A)
Figure 3. VOUT1 (+5V) Output Voltage Regulation
Figure 4. VOUT2 (+15V) Output Voltage Regulation
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MAX5052A Evaluation Kit Evaluates: MAX5052A
IN D8 C16 15F 35V C12 0.22F
FB_P D6 R7 1.2k R12 1.2k D7 OPEN L2 5 15T 4 8 3 7 6T 6 D1 C3 68F 6.3V C6 0.0047F 250VAC L1 VOUT1 C13 1F C4 22F 6.3V SGND T1 9 10 D2 C5 47F 25V D5 C15 1F VOUT2
+VIN +VIN
R6 33k
12T
SGND
FB_P
C1 1F 100V
C2 1F 100V
R8 OPEN
C10 OPEN
28T 2 35H 1 D3 OPEN
D4
R1 22.6k 1% R2 2.49k 1% +VIN R3 1M 1% C14 0.022F R9 14.3k 1% C9 2200pF
IN 2 VIN 8 C11 0.22F 6 NDRV R11 100 C8 OPEN 7 C7 0.22F VCC GND 5 R10 0
FB
6 5 4 1
7 8 N1 3 2
3
COMP
U1 MAX5052A
1 C17 OPEN
UVLO/EN
CS
4
-VIN
R4 42.2k 1%
R5 0.170 1%
SHDN
JU1
NOTE: MOSFET N1 = IR IRF7464
Figure 5. MAX5052A EV Kit Schematic
6
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MAX5052A Evaluation Kit Evaluates: MAX5052A
Figure 6. MAX5052A EV Kit Component Placement Guide--Component Side
Figure 7. MAX5052A EV Kit PC Board Layout--Component Side _______________________________________________________________________________________ 7
MAX5052A Evaluation Kit Evaluates: MAX5052A
Figure 8. MAX5052A EV Kit PC Board Layout--Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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